Hard metal alloy



PATENT 1,:

Clarence W. Balke, Highland Park, Ill., asaignor to Ramet Corporation of America, North Chicago,\llll., a corporation of Illinois No Drawing.

Application February 5, 1938,

Serial a 88.923

35 Glaims.

plements,

For so much of the subject matter herein disclosed which is also disclosed in my copending United States Letters Patent applications entitled: "Hard metal alloys," Serial No. 498,758,

, m tilled November 28, 1930; "Hard metal alloys,

Serial No. 630,787, filed August 29, 1932; and "Hard metal alloys, Serial No. 670,749, filed May 12, 1933--I claim the priority of said applications.

The invention includes among its objects the tungsten carbide content to produce such an alloy of a hardness sumcient for such uses as well as other uses, and, at the same time, of a strength equal to or greater than the strength of known alloys including suflicient tungsten carbide to 5 produce the hardness required for such uses; and whereby such tool material will minimize "cratering and "glazing" of the work which is undesirable and indicative of tool failures.

Other objects and advantages will appear more fully from the following description.

The following formulas are illustrative of alloys within the contemplation of my invention, the percentages given being by weight:

provision, of a novel and improved alloy which 15 may be employedas a tool material that is sub- Example 1 stantially free from the objectionable action a Per cent known as cratering. By cratering I mean the mgsten carbide 12 action of the chips from the work in adhering I mgsten-metal 1 t r w arin away the cuttin ed e supp rtin Tantalum carbide 14.51 a

material of the tool, thereby tending to cause 0'84 cutting edge and eventually tool failures. Cobalt 331 Other objects of the invention include the pro- Nickel 2.21 vision oi substantially a non-cratering tool alloy comprising a plurality of carbides of hard re- Example 2 fractory metals combined with one or more Y Per ent metals, preferably of the iron group, and where sten carhmp 71 21 desired with one or more of the hard refractory sten meta} metals not combined with carbon. t a; 1,

, A further object of the invention is the pro- Iran vision of such a novel alloy wherein the hard recobalt fractory metal carbides are tungsten carbide and N1 ckel another hard carbide having a lower coeificient of thermal conductivity than tungsten carbide. Example 3 a The objects of the invention also include the provision of a novel and improved alloy which Per may be characterized generally by the small Tungsten carbide 70-58 amount of tungsten carbide as compared with Tungsten metal known tool alloys, by the composition of what I Tantalum 14-40 a shall hereinafter term "the auxiliary material,"

meaning thereby the ingredients other than tung- 9 sten carbide, and by the feature of great strength Nlckpl and toughness without the undesirable result of diminished hardness, which has heretofore been Example 4 5 a serious impediment to the provision of alloys Per cent Q of the strength and toughness desired for use in Tungsten carbide S bsta ia y eq al the fabrication of, for example, tools and wire- Tantalum carbide parts drawing dies. Iron group metal 3-15.

Further objects of the invention include the provision of an alloy, suitable for use as a tool Example 5 l material or as wire-drawing dies, wherein the Percent tungsten carbide content is at most 79 per cent Tungsten carbide 62 by weight, and may be only 68 per cent by weight Tungsten metal ll of the alloy; wherein an acid-resistant auxiliary Tantalum carbide 25 material is combined with this relatively small Iron group metal Remainder r .lcapable of excellent performance in turning or .mixed with the proper amount of carbon to form Example 6 Per cent Tungsten carbide 47 Tungsten metal 7 Tantalum carbide 40 Iron group metal Remainder Example 7 Per cent Tungsten carbide 27 Tungsten metal 7 Tantalum carbide Cobalt Remainder The invention is not, however, limited to precise percentages or proportions of ingredients but contemplates that the mentioned proportions may be varied throughout wide ranges, depending somewhat upon the particular use for which the final alloy is intended or the materials to be turned or otherwise cut, by a tool made of the a by. In other examples of these alloys the tantalum carbide content may be as low as 25 per cent by weight and as high as 80 per cent by weight of the entirealloy. The tungsten carbide content may vary from a minor percentage, say 10 per cent by weight of the entire alloy, up to sufiicient tungsten carbide-to provide with the tantalum carbide a total carbide content ranging from a preponderance, say 75 per cent by weight, to about 97 per cent by weight of the entire alloy, depending upon the auxiliary material and the pfircentages by weight thereof contained in the a oy.

The proportions of ingredients of Example 5 make an excellent tool for turning or otherwise cutting manganese steel having from 12 per cent to 14 per cent of manganese, and other very hard steels.

The proportions of Example 6 produce a tool otherwise cutting cast steel with a Brinell hardness of about 400, steels heat-treated to a Brinell hardness above 250, steels with high sulphur and phosphorus contents such as SAE 1112 and 1120,-

and various cast alloys with Brinell hardnesses of about 300 to be used for example in the fabrication of crank shafts, cam shafts, etc.

A tool made of material in the proportions of Example 7 is especially serviceable in the machining of soft steels which are particularly bad with reference to the cratering of the tool.

While I may start with tantalum carbide powder and tungsten carbide powder prepared by any suitable method, I prefer to carbonize thetantalum and the tungsten in such manner as to remove or to exclude embrittling' impurities such as oxygen. These carbides are preferably prepared by the same method. In this method each of the mentioned refractory metals is intimately a carbide thereof, and the mixture is heated in an atmosphere of dry'hydrogen, or in vacuo, to a temperature sufficient to combine the refractory metal and the carbon. Ordinarily, this temperature in the case of tantalum carbide is about 2000" C. The powders of tantalum carbide and tungsten carbide formed inv this way are mixed together in the desired proportions.

Where desired, the proportion of tantalum to carbon may range from 93.8% to 95 per cent by weight of tantalum to from 6.2 per cent to 5 .per cent by weight of carbon, and the tungsten to carbon proportion may vary from about 93.8 per cent to 97 per cent by weight of tungsten to from 6.2 per cent to 3 per cent by weight of carbon. Whenever the carbon content is insufficient to combine with all of the tantalum and/or all of the tungsten, some of one or both of these metals will be present as free metal in the carbide powders. This free metal has a marked effect upon the properties of the final alloy, as willpresently be described. 1

The tungsten other than the carbide tungsten contributes to the tenacity and strength of the alloy and tends to improve the hardness. The tungsten metal may be added with the other metals of the auxiliary material or it may be provided for in the carburization of the tungsten to form the tungsten carbide. In other words, the tungsten and carbon in powdered form may be heated in an inert atmosphere to a sufllclent temperature 'to combine the tungsten and carbon which are so proportioned that at least 88 per cent of the total tungsten and carbon will be in the form of tungsten carbide, the remainder being tungsten metal. 7 About 78 per cent or 79 per cent of this mixture may then be combined with, as already mentioned, from 5 per cent to 7 per cent of the iron group metals and with tantalum carbide. I

As already mentioned, the carbide powder mixture may include some of one or more of the refractory metals uncombined with carbon. In general, free tungsten improves the hardness where the final heat treatment is carried out in vacuo. If the heat treatment is carried out in the presence of carbon and an inert gas, as

where the pressed bodies are packed in graphite and heat treated in an atmosphere of hydrogen and/or'nitrogen, any free tungsten present will be carbonized in whole or in part. Free tungsten in the original powder is sometimes desirable even though it is completely carbonized during the final heat treatment, as when the pressed bodies are heated in graphite and an inert atmosphere. The final alloy is considerably stronger when a portion of the tungsten carbide is produced during the final heat treatment than it is when all of the tungsten is originally introduced in the form of tungsten carbide.

The carbides of tantalum and tungsten contribute to the hardness of the order or magnitude required for and usually found in hard tool materials, but the auxiliary material, I believe, accounts for the greaterhardness without loss of strength.

By employing both tungsten carbide and tantalum carbide in the alloy of the invention, I obtain not merely the additional hardness, strength,

and toughness of each carbide, but surprisingly enough I achieve the desirable result of tools or tool alloys which will turn or otherwise cut a great variety of materials without substantial cratering.

While I have described tantalum, tungsten and the carbides thereof as the preferred hard refractory metals and carbides, the invention briefly contemplates a mixture of a hard and strong v 2,202,821 from the flfth group of the periodic chart of the elements. Molybdenum and/or a carbide thereof may partially or entirely replace tungsten and/or a carbide thereof, respectively. Molybdenum and tungsten are in the sixth group of the periodic chart of the elements.

According to the embodiment of the invention disclosed in Examples 1 to 3, in the auxiliary material, I employ iron making up from 0.56 per cent to 1.6 per cent by weight of the entire alloy, and at least one other metal of the iron group which, together with the iron, ranges from 5 per cent to 7 per cent by weight of the entire alloy. Thesemetals of the iron group, tantalum carbide, and, if desired, tungsten metal, as distinguished from carbidertungsten, are one preferred auxilia ry material of my invention. Where iron, cobalt, and nickel are employed. the cobalt should preferably be about one-half by weight of the combined proportions of the iron. group'metals, the nickel and iron being so calculated that the iron is present in the above-mentioned proportions, the nickel making up the remainder.

Where the pressed bodies prior to the final heat treatment contain free tungsten and a large amount of tungsten carbide, as compared with the amount of tantalum carbide, I have found that cobalt in some unexplainable way facilitates or readily permits carbonization of the free tungsten during the final heat treatment. In such cases I have observed that the carbonization of the free tungsten during the final heat treatnie'nt is more complete when cobalt is employed in the auxiliary material than when nickel alone is used as the auxiliary material.

Nickel; however, has a distinct effect which is most noticeable in the performance of the novei alloy of the invention when it is used in a tool for turning or otherwise cutting steel. I prefer to employ nickel in the auxiliary material where the amount of tantalum carbideis large as compared with the amount cf tungsten carbide in the alloy. Such a material is hard and strong, and while it is satisfactory 'for certain uses, it is more or less brittle, that is, it is lacking in toughness. If, however, an appreciable quantity of free tungsten is present in such an alloy, the

alloy will be stronger and less brittle.

' I have found that such a material containing as high as per cent tantalum carbide can be obtained, and that in addition to the requisite hardness and strength, it will possess the quality of toughness suficient to make a very serviceable and valuable tool, particularly for the turning of steel. I have found, moreover, that a much smaller quantity of tantalum carbide, in combination with tungsten carbide and a suitable auxiliary material, make an excellent tool for turning or otherwise cutting very hard steels.

The amount and composition of the auxiliary material varies somewhat according to the relative amounts of tantalum.carbide and tungsten carbide, and somewhat according to the intended use of the alloy or the tool made therefrom. The auxiliary material makes up any minor percentage by weight of the alloy, but should not be less than 3 percent by weight of the alloy. In general,cobalt is preferred where tungsten carbide predominates by weight in the alloy, and nickel is preferred where tantalum carbide predominates by weight in the alloy. The hardness of my novel alloy is also affected by the amount of iron, if the proportions of the constituents other than tungsten carbide are maintained constant. In fact, if the amount of iron is considerably increased, the resulting product becomes extremely hard.

Thus it will be seen that each of the metals of the iron group, when used in an auxiliary material, imparts certain desirable properties to and performs certain desirable functions in the final alloy. Each may be used alone'or in combination with one or both of the others, depending upon the desired results.

The auxiliary material of my novel alloy tends to be acid-resisting, particularly when it is made according to Examples 1 to 3. This acid-resistant feature is important in that it accounts for the inertness of the auxiliary material to commonly used acidic lubricants. Such lubricants have attacked auxiliary materials of known tools,

causing the tungsten carbide particles to be released, thereby destroying the working surface of slch tools and greatly shortening their useful li e.

' To the mixture of tantalum carbide powder and tungsten carbide powder the metal or metals of the iron group are added in the form of a powder. The mixed ingredients arethen pressed into bodies of any desired size and shape. The pressed or shaped bodies may be heated in a vacuum or they may be packed in graphite powder and heat-treated in an inert atmosphere of hydrogen and/or nitrogen obtained by crackingfor dissociating ammonia. This heat-treatmentis carried on at temperatures ranging between 1350 and 1450 or 1500 C. for a period up to about one and one-half hours.

While I have described a specific embodiment of the invention wherein one or more metals of the iron group are employed as the auxiliary material, it will be understood that the invention contemplates the use of other auxiliary metals. such as manganese, platinum, vanadium, etc., having a lower melting temperature than that of the carbides, which will set the carbide particles and which, through capillary action during the final heat treatment, will bring about a shrinkage of the pressed bodies to produce a sound, solid material, substantially free from porosity and voids. I do not wish, therefore, to be limited to the iron group metals but desire to avail myself of all changes within the scope of the appended claims.

The alloy of my invention has great strength and toughness, but notwithstanding the relatively small amount of tungsten carbide as compared with known tool materials, my alloy is fully as hard as such known tool materials. In known tool materials, the tungsten carbide content is at least 80 per cent and usually 90 per cent or more of the alloy, and, while the hardness of such materials may be increased by increasing the amount of tungsten carbide, this increase in hardness is accompanied by a decrease in or loss of strength. It is, therefore, necessary in the known materials to find the proportions which give only acceptable results, that is, which sacriflee the maximum hardness to obtain the requisite strength. To the contrary, I have found ures where the cratering action has caused the supporting material adjacent the cutting edge of the tool to be removed by the chip.

Thus I have provided an alloy which will make excellent tools for working, drawing, and machining metals and which is provided with an acid-resistant auxiliary material. When such alloy is formed, for example, as tools or wire drawing dies, the tools and dies are both hard and strong, and they are durable by virtue of this acid-resistant auxiliary material, the low susceptibility to cratering, and the hardness and strength. Such tools seem to withstand the shocks of intermittent cuts that frequently crack or break ordinary tungsten carbide tools.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. A sintered composition containing about 3 to 15 per cent of binder metal including significant amounts of metal of the iron group, the remainder of said composition consisting essentially of about 79 to about 10 per cent of tungsten carbide and about 14' to about 80 per cent of tantalum carbide.

2. A sintered composition gontaining about 3 to about 15 per cent of binder metal including significant amounts of cobalt, the remainder of said composition consisting essentially of about 79 to about 10 per cent of tungsten carbide and Iabout 14 to about 80 per cent of tantalum caride.

3. A sintered composition containing about 3 to about 15 per cent of binder metal including significant amounts of nickel, the remainder of said composition consisting essentially of about 79 to about 10 per cent of tungsten carbide and about 14 to about 80 per cent of tantalum carbide.

4. A sintered composition containing about 3 to about 15 per cent of binder metal including significant amounts of iron, the remainder of said composition consisting essentially of about 79 to about 10 per cent of tungsten carbide and about 14 to about 80 per cent of tantalum carbide.

5. A sintered composition containing a metal binder within the range of about 3 to about 15 per cent, the remainder of said composition consisting of about 79 to about 10 per cent tungsten carbide and about 14 to about 80 per cent of tantalum carbide; said metal binder consisting up to one half, of metal of the sixth group of Mendelejefls Periodic Table of the Elements, and the remainder of said binder consisting of metal of the iron group.

6. A sintered composition containing about 3 to 20 per cent of at least one iron group metal, the remainder of said composition consisting substantially of tantalum carbide and tungsten carbide.

7. A sintered composition containing about 3 to 20 per cent binder metal including significant amounts of cobalt, the remainder of said composition consisting substantially of tantalum carbide and tungsten carbide.

8. A hard and tough alloy comprising tungsten carbide and tantalum carbide, making up together a preponderating percentage-by weight but not more than 97 per cent by weight of the entire alloy, and a metal of the iron group making up a minor percentage by weight but not less than 3 per cent by weight ofthe entire alloy.

9. A hard and tough alloy comprising tungsten carbide and tantalum carbide, making up together a preponderating percentage by weight but not more than 97 per cent by weight of the 10. A hard alloy comprising a plurality of carbides of metals from the groups including tantalum and columbium, and tungsten and molybdenum, making up together from 68 per cent to 97 per cent by weight of the alloy; and one or more metals of the iron group making up the remainder.

11. A hard metal sintered composition containing an appreciable quantity and up to about 20 per cent of a binding metal of the iron group, an

appreciable quantity and up to about 30 per cent of tantalum carbide, the remainder of said com,- position consisting substantially of tungsten carbide.

12. A hard and tough alloy comprising tungsten and carbon in the proportion of from substantially 93.8 per cent to 97. per cent by weight of tungsten to from substantially 6.2% to 3% by weight of carbon, substantially all of the carbon being in the form of tungsten carbide, tantalum and carbon in the proportion of from substantially 93.8 per cent to per cent by weight of tantalum to from substantially 6.2 per cent to 5 per cent by weight of carbon, substantially all of the carbon being in the form of tantalum carbide, the tungsten carbide and the tantalum carbide together making up a predominating percentage by weight but not'more than 97 per cent by weight of the entire alloy, and a plurality of metals of the iron group making up the remainder of the alloy.

13. A hard alloy comprising from 14 per cent to I 80 per cent by weight of tantalum carbide having a carbon content of from 5 per-cent to 6.2 per cent by weight thereof; suflicient tungsten carbide, having a'carbon content of from 3 per cent to 6.2 per cent by weight thereof, to provide with said tantalum carbide a total carbide'content 01' from 68 per cent to 97 per cent by weight of the alloy; and one or more metals of the iron group.

14. A hard and tough tool alloy comprising. substantially equal portions of a plurality of reup together from a preponderating percentage by weight to 91 per cent by weight of the alloy, and

a plurality of iron group remainder. I

16. A hard and tough tool alloy composed mainly of tungsten carbide but including, in addition to said tungsten-carbide, from 21 per cent to 32 per cent by weight of a strong auxiliary material comprising iron in the range of 0.5 per cent-to 1.6 per cent by weight of the entire alloy, tungsten metal making up from 3 per cent to 10 per cent by weight of the alloy, and tantalum carbide.

17. A' hard and tough tool alloy composed mainly of tungsten carbide but including, in addition thereto, from 21 per cent to 32 per cent by weight of an acid-resistant auxiliary material comprising tantalum carbide ranging from 14 per metals making up the cent to 17 per cent by weight of the alloy, tungsten making up from 10 to 3 per cent of the alloy, and a plurality of iron group metals.

18. A hard metal sintered composition, consisting essentially of from 68 per cent to '79 per cent of tungsten carbide bonded by an alloy binder containing from 5 per cent to l per cent of an iron group metal and from 14 per cent to 17 per cent of tantalum carbide.

19. A hard metal sintered composition, consisting essentially of from 68 per cent to 79 per cent of tungsten carbide bonded by a tantalumcarbon, wherein the sum of the tungsten and carbon makes up about 78 per cent by weight of the alloy, at least 88 per cent by weight of such sum of tungsten and carbon being tungsten car-= bide, the remainder of such sum of tungsten and carbon being tungsten metal, and the tantalum carbide, metals of the iron group, and said tungsten metal making up an acid-resistant auxiliary material in the range of from 21 per cent to 32 per cent by weight of the entire alloy. v

22. In an alloy including from 63 per cent to 79 per cent by weight of tungsten carbide, an acidresistant auxiliary material making up from per cent to 21 per cent by weight of the alloy and comprising one or more metals from the group including iron, cobalt, and nickel, ranging between 5 per cent and 7 per cent by weight of the alloy, and tantalum carbide.

23. In an alloy including from 68 per cent to 79 per cent by weight of tungsten carbide, an acidresistant auxiliary material making up from 32 per cent to 21 per cent by weight of the alloy and comprising tantalum carbide making up from 14 per cent to 17 per cent of the alloy, one or more metals from the group including iron, cobalt, and nickel, ranging between 5 and 7 per cent by weight of the alloy, and tungsten metal.

24. A hard and tough alloy of tungsten carbide and an acid-resistant auxiliary material, wherein the tungsten carbide makes up from 68 per cent to 79 per cent by weight of the alloy, and the acid-resistant auxiliary material makes up the remainder, said auxiliary material comprising iron and another metal of the iron group making up together from 5 per cent to 7 per cent by weight of the alloy, and tantalum carbide.

' 25. A hard and tough alloy of tungsten carbide and an auxiliary material wherein the tungsten carbide makes up from 68 per cent to 79 per cent by weight of the alloy and the auxiliary material makes up the remainder, and includes iron in the range of from 0.5% to 1.6% by weight of the entire alloy, another metal of the iron group together with the said iron making up from 5 per cent to 7 per cent by weight of the entire alloy, and tantalum carbide.

26. An alloy composed of tungsten and carbon, together making up from 68 per cent to 79 per cent by weight of the alloy, substantially all of the carbon being combined with sufficient tungsten to provide tungsten carbide making up at least 88 per cent by weight of the tungsten and carbon together; from 2.5 per cent to 3.5 per cent by weight of cobalt; from 0.5 per cent to 1.6 per cent by weight of iron; sufficient nickel to bring the sum of the iron, cobalt, and nickel percentages up to from 5 per cent to '7 per cent by weight of the entire alloy; and tantalum carbide making up the remainder.

27. An alloy composed of from 68 per cent to 79 per cent by weight of tungsten carbide, from 2.5 per cent to 3.5 per cent by weight of cobalt, from 0.5 per cent to 1.6 per cent by weight of iron, sufficient nickel to bring the sum of the iron, cobalt, and nickel percentages up to from 5 per cent to 7 per cent by weight of the entire alloy, and tantalum carbide making up the remainder.

28. An alloy composed of from 70 per cent to '72 per cent of tungsten carbide, from 2.5 per cent to 3.5 per cent of cobalt, from 0.5 per cent to 1.6 per cent of iron, substantially 8 per cent of tungsten metal, sufiicient nickel to bring the sum of the iron, cobalt and nickel up to from 5 per cent to 7 per cent of the entire alloy, and tantalum carbide making up the remainder.

29. In a tungsten carbide alloy, from 3 per cent to per cent by weight of tungsten metal, from 5 per cent to 'l per cent by weight together or iron and at least one other metal of the iron group, and tantalum carbide making up the remainder.

30. A hard and tough alloy of tantalum, tungsten, carbon and nickel in the following proportions by weight: a minor percentage but not less than 3 per cent of nickel, and substantially equal proportions of tantalum carbide and tungsten carbide making up the remainder.

31. An alloy composed of the following in substantially the indicated proportions by weight: 71 per cent tungsten carbide, per cent tantalum carbide, 8 per cent tungsten, 2 per cent nickel, 3 per cent cobalt, and 1 per cent iron.

32. A sintered composition containing about 3 to per cent of binder metal including significant amounts of one or more iron group metals, the remainder of said composition being made up of at least one carbide from the group consisting of tungsten carbide and molybdenum carbide and substantial and significant amounts of at least one carbide of a refractory metal said carbide having a lower coemcient of thermal conductivity than tungsten or molybdenum carbide.

33. A sintered composition containing about 3 to 20 per cent of binder metal including sigfinicant amounts of one or more iron group metals and at least one metal of the sixth group, the remainder of said composition being made up of at least one carbide from the group consisting of tungsten carbide and molybdenum carbide and substantial and significant amounts of at least one carbide of a refractory metal said carbide having a lower coeflicient of thermal conductivity than tungsten or molybdenum carbide.

34. A. hard and tough sintered alloy comprising a carbide of a hard refractory metal from the group consisting of tungsten and molybdenum, a

said first mentioned carbide, said carbides together making up not more than 97 per cent by weight and not less than 80 per cent by weight of the entire alloy and binder metal including ductivity than tungsten or molybdenum carbide;

both nickel and cobalt together making up the a carbide of a metal from the group consisting remainder of the alloy. of tungsten and molybdenum making up with 35. A hard sintered alloy comprising from 14 the first said carbide from 80 per cent to 9'7 per to 80 per cent by weight of a carbide of a recent by weight 01' the alloy, and one or more 6 fractory metal said carbide being less metallic metals of the iron group.

and having a lower coeflicient of thermal con- CLARENCE W. BALKE.

CERTIFICATE OF CORRECTION. I

Patent No. 2,2o2,821. June 1;, 191w.

' CLARENCE w. BALKE.

It is hereby certified that error appears in the' printed Specification of the above numbered patent requiringporrection as follows: Page 5, first line 57, claim 22, after the word "from" insert --52--; page 6, first column, lines 6and 7, claim 55, strike out 'beingless metallic and"; and that the said Letters Patent should be read with this correction therein that the same may conform'to the record of the case in the Patent Office.

Signed and sealed this 50th day of July, A. D 191;.0.

Henry Van Arsdale, (Seal) I v Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,202,821. June 11., 191m.

' CLARENCE w. BALKE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiringporrectionas follows: Page 5, first .column, line 57, claim 22, after the word "from" insert --52--; page 6,

first column, lines 6 and 7, claim55, strike out "being less metallic and";

and that {the said Letters Patent should be read with this correction therein that the same may conform'to the record of the case in the Patent Office.

signed and sealed this 50th day of July, A. 'D'. 191m.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents. 

